Datasheet

 2013-2015 Microchip Technology Inc. DS00001987A-page 75

LAN8740A/LAN8740Ai

4.2.16 TDR CONTROL/STATUS REGISTER

Index (In Decimal): 25 Size: 16 bits

Bits Description Type Default

15 TDR Enable

0 = TDR mode disabled

1 = TDR mode enabled

Note: This bit self clears when TDR completes

(TDR Channel Status goes high)

R/W

NASR

14 TDR Analog to Digital Filter Enable

0 = TDR analog to digital filter disabled

1 = TDR analog to digital filter enabled (reduces noise spikes during TDR

pulses)

R/W

NASR

13:11 RESERVED RO -

10:9 TDR Channel Cable Type

Indicates the cable type determined by the TDR test.

00 = Default

01 = Shorted cable condition

10 = Open cable condition

11 = Match cable condition

R/W

NASR

00b

8 TDR Channel Status

When high, this bit indicates that the TDR operation has completed. This bit

will stay high until reset or the TDR operation is restarted (TDR Enable = 1)

R/W

NASR

7:0 TDR Channel Length

This eight bit value indicates the TDR channel length during a short or open

cable condition. Refer to Section 3.8.11.1, "Time Domain Reflectometry (TDR)

Cable Diagnostics" for additional information on the usage of this field.

Note: This field is not valid during a match cable condition. The Cable

Length Register must be used to determine cable length during a

non-open/short (match) condition. Refer to Section 3.8.11, "Cable

Diagnostics" for additional information.

R/W

NASR

00h